March 2011 before spiralling into a war after a crackdown by authorities.
It has provided financial aid and military support, largely in the form of military advisors.
Iranian-backed Hezbollah, the Lebanese movement, has also dispatched fighters to Syria to boost Assad’s forces.
But Assad, in an interview with French television this month, denied that Iranian troops were fighting on the ground.
Meanwhile, Nearly 150 Syrian soldiers have been besieged inside a hospital in Jisr al-Shughur since opposition forces including an al-Qaeda affiliate seized the town last week, a monitor said on Thursday.
The Syrian Observatory for Human Rights said that separately another 200 people — regime forces and their families, captured from Jisr al-Shughur and its surroundings in the northwestern province of Idlib — were being held hostage.
Earlier this week, the Syrian government said a “massacre” of some 200 civilians had taken place in the region of Jisr al-Shughur, which fell on Saturday to a coalition of al-Qaeda affiliate Al-Nusra Front and other opposition groups.
“Nearly 150 soldiers and some civilians are besieged inside a hospital building and there were violent clashes on Thursday between them and rebels” outside the building, Observatory director Rami Abdel Rahman said.
Syria’s Al-Watan newspaper, which is close to the government, appeared to make reference to the same group on Thursday, saying “soldiers were engaged in heavy fighting” against “thousands of terrorists” in the vicinity of the hospital.
The Observatory said Al-Nusra and other rebel groups in control of Jisr al-Shughur had tried to take the building in an unsuccessful attack on Wednesday.
Separately, the monitor said, some 200 people were being held by Al-Nusra and allied forces.
The Observatory said they had been taken hostage from Jisr al-Shughur and the nearby Ishtabraq area during the battle for the town.
On Monday, the foreign ministry sent a letter to the United Nations alleging that “terrorists have massacred nearly 200 civilians, the majority of them women and children, in Ishtabraq.”